Breast cancer is a disease in which cancer cells grow in the breast tissue. It is the most common cancer in women in the United States. The normal breast consists of glandular tissue called lobes. These lobes are sectioned off into lobules, which produce milk. Milk is carried to from the lobules to the nipple by small ducts. All this tissue is surrounded by fatty and connective tissue, as well as blood and lymph vessels. Types of breast cancer found in women are:

Breast cancer is a disease in which cancer cells grow in the breast tissue. Although male breasts do not fully develop, they do contain most of the same basic breast structures as women. Male breasts include small glands called lobules, ducts, and the nipple. These structures are also surrounded by fatty tissue. All of these structures are susceptible to developing breast cancer. Breast cancer in men is rare. This makes awareness of the disease uncommon. Types of breast cancer found in men are:

Mastalgia is breast pain. There are 2 types of mastalgia: cyclic and noncyclic. Cyclical breast pain is most often associated with menstrual periods. Noncyclical breast pain is not related to the menstrual cycle.

Breasts are composed of ducts, milk glands, and fatty and fibrous tissues. Fibrocystic disease occurs when there are fluid-filled lumps (cysts) of duct tissue. These lumps are surrounded by a scar-like capsule of tissue in the breasts. Although harmless, these lumps can sometimes be the site of pain (mastalgia) that recurs late in each menstrual cycle. The greatest problem with fibrocystic disease is telling the difference between this condition and breast cancer.

Gynecomastia is an enlargement of the breasts in men. This condition is not the same as having a fatty breast area from obesity. The breast tissue is firm in men with gynecomastia. This may occur in up to one-third of men. About 65% of boys will develop some degree of breast enlargement during puberty. This is normal and usually goes away by age 18.